1. Field of the Invention
The present invention relates to traffic signals and the electrical power control circuitry driving them. In particular, this invention deals with light emitting diode (LED) traffic signals controlled via standardized NEMA TS2 load switches. More specifically, this invention introduces a system where a single power supply placed inside the load switch replaces the three power supplies of three conventional LED traffic signals connected to the load switch.
2. Description of Related Art
LED traffic signals are gaining in popularity, replacing the prior designs using incandescent bulbs. Driven by the stable current and voltage levels produced by switching power supplies, LED traffic signals consume relatively low amounts of power and have extremely long lifetimes compared to standard incandescent light bulbs.
Previously, LED traffic lights have been used as a direct retrofit for previously existing incandescent light bulbs. Because most signal installations normally have at least three traffic signals per load switch (red, yellow and green signals), at least three LED power supplies are required. Considering that there is only one traffic signal activated at a time, it is possible, via the present invention, to use only a single power supply per load switch, resulting in significant manufacturing and operating power consumption cost savings.